1. Field of the Invention
The present invention relates a starting clutch control apparatus which controls torque transmitted by a clutch in starting a vehicle.
2. Description of the Prior Art
Conventionally, a method disclosed in Japanese Patent Application Laid-Open Publication No. S63-305039 has been known as an example of a clutch control method for controlling torque transmitted by a starting clutch which connects or disconnects an engine to or from the shift mechanism of an automatic transmission.
In the starting clutch control method described in this publication, the ratio of rotational speeds of a clutch input shaft and a clutch output shaft of the starting clutch is detected, a torque coefficient C corresponding to the present clutch speed ratio is read out from a data map of torque coefficients C set in advance relative to speed ratios, and a clutch control torque Tcl is calculated based on the torque coefficient C and the present engine speed so as to control torque transmitted by the starting clutch.
In the method in which the starting clutch is controlled using the clutch control torque Tcl calculated as above, only one relationship between the gear ratio of the starting clutch and the capacity coefficient C is set, and hence the clutch control torque Tcl cannot cope with sudden operation of an accelerator.
To address this problem, in a method disclosed in Japanese Patent Application Laid-Open Publication No. H09-72353, accelerator operated amount are divided into three ranges, and a data map of torque coefficients C relative to gear ratios of a starting clutch is prepared in advance for each of the three ranges, a data map of these torque coefficients C is complemented by present accelerator operated amount, and calculate clutch control torque Tcl, so that torque transmitted by the starting clutch can be responsive to e.g. sudden operation of an accelerator.
However, in the method in which the data map of torque coefficients C is prepared for each range of accelerator operated amounts so as to calculate clutch control torque Tcl, torque transmitted by the starting clutch can follow changes in accelerator operated amount, but it is necessary to prepare a plurality of data maps of torque coefficients C in accordance with accelerator operated amounts.